Petrological and Geochemical Studies of the Zhubu Magmatic PGE Deposit in the Permian Emeishan Large Igneous Province,SW China

摘要

The Zhubu PGE deposit is a sulfide-poor PGE deposit hosted in a small mafic-ultramafic intrusion which belongs to the Emeishan large igneous province (LIP),western China.The petrological and geochemical data of the Zhubu intrusion have been acquired to investigate the genetic relationship between magma evolution and ore formation.The parental magma of olivine-rich ultramafic rocks in the intrusion is estimated to have ～13 wt.％ MgO,similar to that of the transporting magma of the coeval picrites in the region.It is suggested that PGE mineralization in the Zhubu ultramafic rocks resulted from sulfide segregation due to crustal contamination at depth.Small amounts of immiscible sulfide droplets formed at depth with high R-factors and hence high PGE tenors were brought up by ascending magma and deposited in the base of the Zhubu intrusion.